Contact mounting for electrical devices



Feb. 10, 1942. D. H. LOUKOTA ETAL 2,272,379

CONTACT MOUNTING FOR ELECTRICAL DEVICES Filed Afig. 2, 1940 2 Sheets-Sheet 1 l v v 23 5 mumr/ou 2 DOUGLAS H. Lou/(07:4 RA YMOND C. DURA NT 51 EDWARD J. NE/F/NG RR/S K/ECH FOSTE ARR/5 f nd a u f C Fly! 1 A T TOILNEZXS Feb. 10, 1942. D. H. LOUKOTA ETAL CONTACT MOUNTING FOR ELECTRICAL DEVICES Filed Au. 2, 1940 2 Sheets-Sheet 2 www OA/ sw m 0M5 M D v mp mu 6M WWW DRE 71 ARR/J E A TZ' EZ E Y6 Patented Feb. 10, 1942 stares ur ci ics CENTA'CT MOUNTING F03 ELECTRIQJAL DEVICES Douglas H. Louliota and Raymond C. Durant, Pasadena, and Edward J. Neifing, Los Angeles, Calif... assignors to James Cannon, ILos Angelica, 'Calii.

i9 Claims.

Our invention relates to electrical devices in general, with special reference to contacts for electrically interconnecting conductors, and is directed specifically to an improved method and construction for mounting such a contact in a cooperating insulating support.

While our invention is applicable widely in the electrical art, it is now being incorporated most widely in such connecting fixtures as receptacles and plugs in wall fittings and cable connectors. For the purpose of disclosure, we elect to describe such an embodiment of the invention, but

"those skilled in the art will readily appreciate that the invention is adaptable to other electrical devices and suflicient guidance will be found herein for applying the invention wherever it may be useful.

A typical receptacle or plug fitting for electric cables and flexible conduit for electric wires comprises a fitting housing, an insulator in the housing, and one or more male or female contacts mounted in the insulator for cooperation with complementary contacts in complementary fittings. in the usual construction the contacts are permanently mounted in the insulator.

One problem that arises in the employment of a conventional fitting is that electric conductors must be soldered to the contacts in making an installation and heat employed in the soldering operation is necessarily conducted through the material of the contact to the insulator in which it is mounted. If a contact is relatively small in diameter, the soldering operation may be performed Without any serious heating or the insulator, but if the contact is relatively large the necessary heating of the contact will inevitably damage the insulating body.

Another problem arises when a contact becomes damaged or otherwise unserviceable. The contact in such event must be replaced, and if the contact is mounted in the insulating body in a permanent manner, it becomes necessary to replace not only the damaged contact but also the insulator and all of the other contacts mounted therein. Often, the insulator is permanently mounted in the surrounding fitting housing and the fitting housing must also be replaced.

One object of our invention is to provide for detachably mounting a contact in an insulator whereby the contact may be removed at will. It is contemplated that such a contact may be removed from the insulator in a convenient manner for the soldering operation and then remounted after. the heat of the soldering operation is dissipated, thereby avoiding any danger of heat damage to the insulator.

Another object of our invention is to achieve an efficient and positive attachment oi a contact to an insulator by relatively simple structure that is inexpensive and readily assembled.

The preferred form of our invention is characterized by the conception oi a threaded, or more specifically, a bayonet-type mounting for the contact in the insulator in combination with means to lock the contact against release from engagement with the insulator. One of our more specific objects is to provide such a construction in which the locking means is releasably held in a locking position at which it prevents relative rotation of the contact that is necessary to release the contact from the surrounding insula tor. A further object is to provide by a relatively simple structure a groove that is required in either the contact or in the insulator for the bayonet action, and in this regard a feature of our invention is the conception of a laminated insulator ..the layers of which are variously apertured to provide such a groove.

A still further object of our invention is to maintain a floating mounting for a contact to permit a desirable degree or relative movement on the part of an installed contact.

Other objects and advantages of our invention will be apparent from our detailed description to follow, considered with the accompanying drawings, in which: I

Fig. 1 is a side elevation of our invention embodied in a wall plug;

Fig. 2 is a longitudinal section through the wall plug of Fig. l, the wall plug being shown in engagement with a cord receptacle that is partially in section and partially in side elevation;

Fig. 3 is an end view of the wall plug taken as indicated by the arrow 3 in Fig. 2, the detachable contact being removed from the plug;

Fig. 4' shows in perspective the separate 1aminations of the insulator employed in the wall p s;

Fig. 5 is a. side elevation of the contact member of the Wall plug;

Fig. 6 isan end view of the contact;

Fig. 7 is a perspective view of a locking means that may be employed in the combination;

Figs. 8 to 10 are transverse sections taken as indicated by lines 88, 99, and I 0-) of Fig. 2;

Fig. 11 is a perspective view of a locking means Employed in a second embodiment of our invenion;

Fig. 12 is a side elevation 01 a contact member designed for use with the locking means of Fig.

a preferred form of our invention is incorporatedis adapted to be mounted, for example, ina panel or wall member 2i for use in the manner indicated in Fig. 2. The wall plug has a barrel or cylindrical body 22 with a radial flange 23. In the particular installation shown, the barrel 22 is inserted in an aperture 25 in the panel 2i and is held in place by suitable screws 26 through the flange 23. The barrel 22 of the wall plug is adapted to receive telescopicall a mating barrel 21 of, for example, a receptacle generally designated 23, the particular receptacl depicted being a connector mounted on the end of 9. flexibleconduit 30. To form interconnection between the wall plug and the receptacle, the barrel 22 or the wall plug may be threaded for engagement by a gland nut 3| that is rotatably mounted on the barrel 21 in engagement with a radial flange 32. Where a waterproof connection is desired, a suitable gasket 33 is usually inserted between the end of the barrel 21 and an annular shoulder 35 in the barrel 22.

Mounted in an insulator generally designated 33 in the barrel 22 or the wall plug is a contact or prong member 31 for electrical cooperation with a complementary contact or receptacle member 33 in the receptacle 28. The present invention pertains to the manner in which the contact 31 is mounted in the insulator38 and obviously applies to either a prong or receptacle type of contact.

In our invention it is contemplated that either the insulator member 36 or the contact member 31 will have a groove, and the other member will be formed for cooperation with the groove to the end that the contact member may be inserted and rotated in the insulator member for engagement therewith against axial movement, and it is further contemplated that some suitable looking means will be provided to prevent relative rotation of the contact member out of such position of engagement with the insulator member. Preferably the lock-ing means engages one or the other member to preventth'e locking means from moving out of its eilective position. In the preferred form of our invention we provide for bayonet-type releasable engagement between thecontact member and the surrounding insulator, a bayonet groove being provided in th insulator and a complementary shoulder being formed on the contact for cooperation with the groove.

The insulator 38 may be a single body of unitary fabrication, but in the preferred form of our invention the insulator is formed by an assembly of three discs, an inner disc 40, an intermediate disc 4|, and an outer disc 42, outer here reierring to the rear end of the wall plug shown in face view in Fig. 3. The insulator assembly may be secured in the barrel 22 in any suitable manner. In the particular construction shown, the assembly of discs is confined between an annular shoulder 43 in the barrel 22 and a split ring or "snap wire" 45' or square cross-section 7 also extends through a. complementary notch II cut in the margin of each ring. It will be noted that the split ring 45 serves as a keeper for the spline 41 as well as for the assembly of discs.

The configurations and functions of the three discs 45-42 may best be explained after referring to the construction of the complementary contact member 31.

The metal contact member 31 has a cylindrical body 5| with an inner face 52 from which a prong portion 53 extends longitudinally. Since a shoulder or other engagement means must be presented by the contact member 31 for engagement with a complementary groove in the insulator assembly, the contact member 31 is provided with at least one radial flange or lug 55,

there being two such lugs diametrically opposite each other in the preferred form of th contact. In the manufacture of the particular construction shown in Figs. 5 and 6, the plug is machined to form a radially extending annular flange which is then cut away along the parallel faces 56 to form the two radial lugs 55. The rear end of the contact body 5| forms a cylindrical recess 51 (Fig. 2) which is preferably tinned to facilitate the soldering oi. a conductor to the contact, Fig. 2 showing a wire 58 so soldered.

The inner disc 40 which rests against the annular shoulder 43 has an aperture 60 dimensioned to receive the prong portion 53 of the contact member 31 so that the face 5! of the disc may abut the face 52 of the contact to limit axial movement of the contact forward through the insulator assembly. The second disc 41 has a larger aperture 62 of sufllcient diameter to clear the ends of the two engagement lugs 55. Finally, the outer disc 42 has an aperture 63 of a diameter smaller than the diameter across the lugs 55 but great enough to receive the cylindrical body 5|, and diametrically opposite recesses or notches 65 complementary to the lugs 55 are provided in the outer disc to permit the two lugs'to be moved past the outer disc into the plane of the intermediate disc 4|.

It is apparent from the above description and from reference to Figs. 2, 3, and 4 that the three discs 40-42 cooperate to form an annular groove 65 to which the lugs 55 01 the contact member 31 may be admitted through the notches 65. It may be said that the three discs, in effect, form at least one bayonet groove or slot, the axially extending portion of the bayonet slot being provided by one of the notches 65 and the arcuate portion of the slot to permit relative rotation being provided by the annular groove 86. When the contact member is moved axially into the insulator assembly with th two lugs 55 aligned with the notches 85, the lugs are carried into the plane of the intermediate disc 4i and only slight rotation of the contact member relative to the insulator assembly is then necessary to lock the contact member against relative axial movement. The essential fact in the cooperating relationship is that the contact member may be rotated into a position at which a shoulder thereon engages a complementary shoulder of the insulator, and when the combination is viewed in this aspect, it is apparent that each of the lugs 55 forms an engagement shoulder 61 (Fig. 5) to cooperate with a complementary engagement shoulder 88 (Figs. 2 and 4) formed by the outer disc 42.

While the particular wall plug shown in Fig. 2 has only one contact 31, more often than not such a wall plug has a plurality of prongs of various sizes adapted to cooperate with complementary contacts in complementary receptacles. In practice, it is highly desirable that such numerous prongs mounted in a common insulating assembly be given a certain flexibility of freedom for lateral movement to compensate for minor variations in the spacing and alignment of the contacts. One of the features of the construction shown in the drawings is that we may provide any required degree of such tolerance by making the contact-receiving apertures of the three discs iii-42 somewhat oversize relative to the contact member 31 and by making the intermediate disc somewhat oversize in thickness relative to the thickness of the two lugs 55, thereby achieving what may be called a floatingly mounted contact.

The locking means contemplated in our invention to prevent rotation of the contact member out of the bayonet engagement with the insulator assembly is preferably releasably engaged with the contact member for maintenance in its effective position. In the particular construction shown in the drawings we provide a latching shoulder It on the contact member 3'! by cutting a circumferential groove H in the cylindrical body El and employ for our locking means a simple metal clip generally designated M in Fig. 7. The locking clip 12 comprises a resilient split ring portion 15 and integral therewith a key portion 16 dimensioned to fit longitudinally into one of the notches 65 in the outer disc 42- v After the contact member 3! is inserted in the insulator assembly and rotated to carry the lugs 55 out of alignment with the notches 65, the clip I2 may be slipped onto the cylindrical body of the contact member with the key portion I8 extending through one of the notches 65 into the plane of the intermediate disc M. At the effective position of the clip 72 the split ring portion I5 embraces the contact body iii in the circumferential groove H and is thereby retained against accidental removal. Release of the contact member while the key 16 is in its efiective position is prevented because rotation of the contact member in either rotary direction is stopped by abutment of one of the lugs 55 with the key portion, the key portion being and dismounted from the insulator 36 at will. In

the procedure of installing such an electrical fitting in some particular electric circuit, the contact member is temporarily removed from the insulator for the soldering operation and is replaced after the contact member cools sufficiently to avoid any possible damage to the insulator. After a period of service in the given installation, the contact member may be removed for replacement, if necessary, or may be removed in the described manner for mounting the wire 58 in some other electrical fitting of similar construction.

The second embodiment of our invention illustrated by Figs. 11 to is similar to the first embodiment described above ,except that the locking clip 85 of Fig. ll'is substituted for the locking clip I2 of Fig. 'I, and the contact member 81 of Fig. 12 may be substituted for the contact member 31 of Fig. 5. Other parts of the device are unchanged and in Figs. 14 and 15 are designated by the same numerals as heretofore em- I ployed.

The new locking clip 85 has two key portions or looking tongues 88 disposed diametrically opposite from each other to enter the two notches or recesses of the insulating member 36. The ends 98 of the locking tongues 88 are deformed or bent for releasable engagement with the contact member 81 so that the two tongues not only serve to lock the assembled contact member against rotation, but also serve to anchor the locking clip.

The contact member 81 is similar to the previously described member 31, but lacks a circumferential groove since such a groove is not necessary for retaining the locking clip 85. The contact member 8'! has a cylindrical body 9| with an inner face 82 from which extends a prong portion 93, and the contact member has two radial flanges or lugs 95 to cooperate with the insulating body 38 in the manner previously described. The rear end of the contact body 9| forms the usual cylindrical recess 91.

I The second embodiment of. our invention is assembled in much the samemanner as the first embodiment. The contact member 81 is inserted in the insulator assembly and rotated to carry the lugs 85 out of alignment with the notches 65 of the insulator 38. The locking clip 85 is then slipped onto the cylindrical body 9| and shifted along the contact member until the end portions of the locking tongues 88 snap into engagement with the contact member at the inner face 92, as best shown in Figs. 13 and 15. The locking clip 85 may be removed at will by applying sufiicient force longitudinally to dislodge the ends 90 of the locking tongues 88. One feature of this form of our invention is that when the locking clip 85 is in assembled disposition, it is exposed sufficiently to permit the use of a screw driver as a pry to force the locking clip out of engagement with the contact member 81. Fig. 15, for example. shows in dotted lines a screw driver I disposed at an angle for insertion into the assembly to pry the locking clip rearward.

It will be apparent to those skilled in the art that the present detailed disclosure exemplifies a number of diverse arrangements based on the same inventive concept, and we specifically reserve the right to all such forms of our invention that come within the terms of our appended claims.

We claim as our invention:

1, In am electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of: an insulating member having a longitudinal passage extending completely therethrough, said member having a rearwardly presented stop surface adjacent said passage, a portion of said passage in the rearward end thereof forming a longitudinal bayonet groove and a locking re cess; a contact member extending through said passage with a portion projecting forward from the passage for electrical contact with said complementary fitting, said contact member havin a forwardly presented stop surface for abutment with said rearwardly presented stop surface to limit forward extension of said projecting portion of the contact member, said contact member having a peripheral bayonet projection for assembly movement through said groove into normal locking position in said recess; and locking means normally extending along said contact member through said groove to block unlocking movement of said bayonet projection, said locking means releasably engaging one of said members to prevent accidental retraction of thelocking means;

2. In an electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of an insulating member having a longitudinal passage extending completely therethrough, said member having a rearwardly presented stop surface adjacent said passage, a portion of said passage in the rearward end thereof forming a longitudinal bayonet groove and a locking recess; a contact member extending through said passage with a portion projecting forward from the passage for electrical contact with said complementary fitting, said contact member having a forwardly presented stop surface for abutment with said rearwardly presented stop surface to limit forward extension of said projecting portion of the contact member, said contact member having a peripheral bayonet projection for assembly movement through said groove into normal locking position in said recess; and looking means extending into said groove to block unlocking movement of said bayonet projection, said locking means being radially flexible for movement into and out of releasable engagement with one of said members to prevent accidental retraction from said groove.

3. A combination as set forth in claim 2 in which one of said members has an annular recess with a rearward wall and in which said locking member normally engages said member in said recess, whereby said rearward wall prevents outward retraction of the locking means from said groove.

4. In an electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of: an insulating member having a longitudinal passage extending completely. therethrough, said member having a rearwardly presented stop surface adjacent said passage, a portion of said passage in the rearward end thereof forming a longitudinal bayonet groove and a locking recess; a contact member extending through said passage with a portion extending rearwardly from said passage and a portion projectingforward from said passage for electrical contactwith said complementary fitting, said contact member having a forwardly presented stop surface for abutment with said rearwardly presented stop surface to' limit forward extension of said projecting portion of the contact member, said contact member having a peripheral bayonet projection for assembly movement through said groove into normal locking position in said recess; and a locking means extending into said groove to block unlocking movement of said bayonet projection, said locking means normally yieldingly embracing said contact member adjacent said forwardly presented shoulder to prevent accidental retraction of the locking means from said groove.

5. In an electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of: an insulating member having a longitudinal passage extending completely therethrough, said member having a rearwardly presented stop surface adjacent said passage, a portion of said passage in the rearward end thereof forming a longitudinal bayonet groove and a locking recess; a contact member extending through said passage with a portion extending rearwardly from said passage and a portion projecting forwardly from said passage for electrical contact with said complementary fitting, said contact member having a forwardly presented stop surface for abutment with said rearwardly presented stop surface to limit forward extension of said projecting portion of the contact member, said contact memberhaving a peripheral bayonet projection for assembly movement through said grooveinto normal locking position in said recess, said contact member having a peripheral recess in said rearwardly extending portion; and locking means extending into said groove to block unlocking movement of said bayonet projection, said locking means yieldingly embracing said contact member in engagement with said peripheral recess to prevent accidental retraction of the looking means from said groove.

6. In an electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of an insulating member having a longitudinal passage extending completely therethrough, said member having a rearwardly presented stop surface adjacent said passage, a portion of said passage in the rearward end thereof forming a longitudinal bayonet groove and a locking recess; a contact member extending through said passage with a portion projecting forward from the passage for electrical contact with said, complementary fitting, said contact member having a forwardly presented stop surface for abutment with said rearwardly presented stop surface to limit forward extension of said projecting portion of the contact member, said contact member having a peripheral bayonet projection for assembly movement through said groove into normal locking position in said recess; and locking means for preventing unlocking movement of said bayonet projection, said locking means comprising a flexible split ring normally engaged with one of said members and a projection extending forward from said split ring into said groove.

'7. In an electrical connecting fitting movable into and out of engagement with a. complementary connecting fitting, thecombination of: an insulating member having a longitudinal passage extending completely therethrough, the rearward portion of said passage being of noncircular cross section, an intermediate portion of said passage forming a locking recess, the portion of the passage forward of said recess being of smaller cross-sectional dimension than said rearward portion of the passage; a contact member extending through said passage with a portion projecting forward from the insulating body for electrical contact with said complementary fitting, said contact member having a peripheral bayonet projection normally extending in lock-' ing position into said locking recess, the crosssectional dimension of the contact member at said bayonet projection being greater than the cross-sectional dimension of said forward portion of the passage; and locking means extending through said insulating member to block unlocking movement of said bayonet projection, said locking means being releasably engaged with one of said members to prevent retraction of the locking means.

8. In an electrical connecting fitting movable into and out of engagement with a complementary connecting fitting, the combination of: an insulating member having a longitudinal passage extending completely therethrough, the rearward portion of said passage being of non-circular cross section, an intermediate portion of said passage forming a locking recess, the portion of the passage forward of said recess being of smaller cross-sectional dimension than said rearward portion of the passage; a contact member extending through said passage with a portion projecting forward from the insulating body for electrical contact with said complementary fitting, said contact member having a peripheral bayonet projecting normally extending in locking position into said locking recess, the cross-sectional dimension of the contact member at said bayonet projection being greater than the cross-sectional dimension of said forward portion of the passage; and locking means normally extending into said insulating member to block unlocking movement of said bayonet projection, saidrlocking means having a flexible split-ring portion for releasable engagement with one of said members, said split-ring portion being yieldable to clear said contact member for lateral removal of the locking means.

9.- A combination as set forth in claim 7 in which said insulating member comprises an assembly of at least three bodies, one body being apertured to form said forward portion of said passage, one body being apertured to form said locking recess, and one body being apertured to form said rearward portion of said passage.

DOUGLAS H. LOUKOTA. RAYMOND C. DURANT. EDWARD J. NEIFING. 

